Add mlmmj

[ng0]

> Hi!  Maybe it just fell through the cracks?  Did you get feedback?

As far as all of guix-devel archive tells me, no.

> Also, "someone else can write" doesn't work as a rule of thumb.  :-)

Yeah, I've figured so much out after all the time :)

> Anyway, if the patch is ready to apply, can you resend it?
> Thanks, and apologies for the delay!

No problem.


So, the problem here will be - as it was with opensmtpd - there's no testsuite, 
we need a service for an MTA and then we can test if it works. I don't see this 
as a hold-up for the package as it will probably work on non-GuixSD hosts.
It would be really nice if all these Mailing applications would have a make 
check phase, but well...